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/*
 * Copyright 2014-2021 Sayi
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.deepoove.poi.render.compute;

import java.util.Map;

import org.springframework.asm.MethodVisitor;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.CodeFlow;
import org.springframework.expression.spel.CompilablePropertyAccessor;
import org.springframework.util.Assert;

/**
 * org.springframework.context.expression.MapAccessor
 * 
 * @author Sayi
 * @version
 */
public class ReadMapAccessor implements CompilablePropertyAccessor {

    @Override
    public Class[] getSpecificTargetClasses() {
        return new Class[] { Map.class };
    }

    @Override
    public boolean canRead(EvaluationContext context, Object target, String name) throws AccessException {
        return (target instanceof Map && ((Map) target).containsKey(name));
    }

    @Override
    public TypedValue read(EvaluationContext context, Object target, String name) throws AccessException {
        Assert.state(target instanceof Map, "Target must be of type Map");
        Map map = (Map) target;
        Object value = map.get(name);
        if (value == null && !map.containsKey(name)) {
            throw new MapAccessException(name);
        }
        return new TypedValue(value);
    }

    @Override
    public boolean canWrite(EvaluationContext context, Object target, String name) throws AccessException {
        return false;
    }

    @Override
    public void write(EvaluationContext context, Object target, String name, Object newValue) throws AccessException {
    }

    @Override
    public boolean isCompilable() {
        return true;
    }

    @Override
    public Class getPropertyType() {
        return Object.class;
    }

    @Override
    public void generateCode(String propertyName, MethodVisitor mv, CodeFlow cf) {
        String descriptor = cf.lastDescriptor();
        if (descriptor == null || !descriptor.equals("Ljava/util/Map")) {
            if (descriptor == null) {
                cf.loadTarget(mv);
            }
            CodeFlow.insertCheckCast(mv, "Ljava/util/Map");
        }
        mv.visitLdcInsn(propertyName);
        mv.visitMethodInsn(INVOKEINTERFACE, "java/util/Map", "get", "(Ljava/lang/Object;)Ljava/lang/Object;", true);
    }

    @SuppressWarnings("serial")
    private static class MapAccessException extends AccessException {

        private final String key;

        public MapAccessException(String key) {
            super("");
            this.key = key;
        }

        @Override
        public String getMessage() {
            return "Map does not contain a value for key '" + this.key + "'";
        }
    }

}